dennismonsewicz on "Overriding default new user registration email"

I created a plugin that should override the default WP new registration email, but it isn't working.

I created a file in my plugins directory called welcome_email_override.php, activated it and when I register a test user, the default WP email is still sent.

Is there anyway to do this without modifying the pluggable.php file?

Here is my code:

<?php

/*
Plugin Name: wp_new_user_notification change subject line
Plugin URI: http://www.premiumstockmusic.com
Description: wp_new_user_notification changing the subject line
Author: Dennis Monsewicz
Version: 1
Author URI: http://dennismonsewicz.com
*/

/**
 * Notify the blog admin of a new user, normally via email.
 *
 * @since 2.0
 *
 * @param int $user_id User ID
 * @param string $plaintext_pass Optional. The user's plaintext password
 */

if ( !function_exists('wp_new_user_notification') ) {

 function wp_new_user_notification($user_id, $plantext_pass = '') {
   	$user = new WP_User( $user_id );

		$user_login = stripslashes( $user->user_login );
		$user_email = stripslashes( $user->user_email );

		$message  = sprintf( __('New user registration on %s:'), get_option('blogname') ) . "\r\n\r\n";
		$message .= sprintf( __('Username: %s'), $user_login ) . "\r\n\r\n";
		$message .= sprintf( __('E-mail: %s'), $user_email ) . "\r\n";

		@wp_mail(
			get_option('admin_email'),
			sprintf(__('[%s] New User Registration'), get_option('blogname') ),
			$message
		);

		if ( empty( $plaintext_pass ) )
			return;

		$message  = __('Hi there,') . "\r\n\r\n";
		$message .= sprintf( __("Welcome to %s! Here's how to log in:"), get_option('blogname')) . "\r\n\r\n";
		$message .= wp_login_url() . "\r\n";
		$message .= sprintf( __('Username: %s'), $user_login ) . "\r\n";
		$message .= sprintf( __('Password: %s'), $plaintext_pass ) . "\r\n\r\n";
		$message .= sprintf( __('If you have any problems, please contact me at %s.'), get_option('admin_email') ) . "\r\n\r\n";
		$message .= __('Adios!');

		wp_mail(
			$user_email,
			'Welcome to Premium Stock Music',
			$message
		);
 }

}
?>